At a Maui aquarium a Hawaiian green turtle makes a guest appearance. Members of this threatened species are unique among sea turtles for their herbivorous diet, thought to imbue their fat with a greenish hue.

PHOTO: JOSE CARDONA

Fluttering wings leave lacy trails as moths beat their way to a floodlight on a rural Ontario lawn. The midsummer night’s exposure, held for 20 seconds, captured some of the hundreds of insects engaged in a nocturnal swarm.

PHOTO: STEVE IRVINE

Stone walls on Isla Guañape Norte prevent precious bird droppings, called guano, from falling into the Pacific. Coveted as fertilizer, the dung must be reaped by hand. Here a worker returns sifted-out feathers and bones.PHOTO: TOMAS MUNITA

EDITORS’ CHOICESerena AmaduzziRome, ItalyWalking around Havana, Cuba, after a thunderstorm, Amaduzzi, 23, stopped to watch two men fixing a broken-down car. “I saw a cute little face inside it, staring at me, and I smiled,” she says. When the child’s eyes smiled back, “it was like we’d shared a mute conversation.”

READERS’ CHOICEEllen CaseBaton Rouge, Louisiana“This mosquito was trapped in a bead of cooking oil in a dish of water,” says Case, 57. “I noticed it when I went to clean up the mess I’d made earlier,” while working at home on a series of close-up shots. The refracted colors are from a plastic tablecloth beneath the dish.

World Beneath the WavesPeople do beautiful things in the water. They become braver and calmer, more fluid and playful. The freedom of buoyancy allows us to act as we truly are.

I grew up near the ocean in Australia, but I didn’t appreciate our ancestral ties to it until I’d spent years living abroad. When I returned, I noticed how people here are drawn to the beaches. The pull is shared—a human equalizer. When you see swimmers in the ocean together, you see them react intuitively to the tide’s push and pull.

I like the clarity of salt water. In the past dozen years my technique and equipment have stayed simple: a deep breath, a small camera, and transparency film, for its dense blacks and saturation. Despite new technologies, the magic of the darkroom still fascinates me.

On hot days I hang out where the waves are forming. Just before they break, I dive to the bottom. A flash of sunlight penetrates the curl and the churn, illuminating the swimmers above. They look like actors dancing or flying on an underwater stage. I take one picture, surface, breathe, and repeat. Shooting 36 frames might take a day.

We love the sea, yet we pollute it. As a mother, I agonize over what my children will inherit. But I’m also optimistic. If we can notice natural beauty, we might learn how to preserve it. —Narelle Autio

PHOTO: NARELLE AUTIO

Narelle Autio is a photographer based in Adelaide, Australia. Her images of the country’s coastal life are exhibited internationally.

PHOTO: NARELLE AUTIO

Swimmers paddle in the clear surf of Sydney’s Freshwater Beach. For many of us the water is a playground. But to me these images show something else: our shared humanity when we’re immersed.

As big waves buffet the eastern Australian coast, a father clings to his son. I get pounded in the same surf as the swimmers, so I never know exactly what my shots will show until I develop them.

PHOTO: NARELLE AUTIO

PHOTO: NARELLE AUTIO

At Bondi Beach near Sydney, a young woman dives to safety as a vast wave rolls overhead. It’s always a nice surprise to me when the light, the wave, and the swimmer come together perfectly in one frame.

PHOTO: NARELLE AUTIO

On the sandy floor of a popular Sydney beach, a girl floats in a prone position, her life held in a breath of air. Despite its many mysteries and dangers, the ocean exerts an elemental pull that draws us back.

Jurassic Mother Lode

Pterosaurs died out with the dinosaurs, leaving more mysteries than fossils. Now paleontologists who study the flying vertebrates are hitting pay dirt. In 2009 a transitional form in pterosaur evolution, Darwinopterus, was found in China. Then the site yielded a 160-million-year-old fossil of one with an egg (right).

The University of Leicester’s David Unwin and colleagues say the latter find bolsters a hypothesis that pterosaurs were sexually distinct: Females had wider hips, and only males had head crests. Other experts agree, but Kevin Padian of the University of California, Berkeley argues that we don’t yet know enough about pterosaur maturation to say whether age or gender accounts for physical differences among fossils. More scrutiny may resolve that flap—and help decipher other abiding pterosaur enigmas. —Jeremy Berlin

This fossil from China’s Liaoning Province reveals a pterosaur—about the size of a small falcon—with an egg (circle).

PHOTO: DING MING, ZHEJIANG MUSEUM OF NATURAL HISTORY

40 Winks?

Life is hard, and mammals need their z’s to slog through it. But why does a chipmunk need about 15 hours of shut-eye a day, when a giraffe needs only 4.5? One answer, says UCLA sleep researcher Jerome Siegel, lies in the varied ways animals have adapted to be energy efficient and to stay safe.Consider elephants, which nod off just three-plus hours a day. “To be so big, they have to eat most of the time,” Siegel says. In contrast, it makes evolutionary sense for brown bats to conserve energy except during the few hours a night when their insect prey is out. A platypus also can feed less and slumber more (14 hours). Why? Maybe because just a little crustacean meal packs a huge caloric punch. As for safety, those mammals that nap in hiding, like bats or rodents, tend to have longer, deeper snoozes than those on constant alert. Of course, a few beasts can slumber anytime, anywhere. Says Siegel, “Who’s going to mess with a sleeping lion?” —Jennifer S. Holland

Giraffes sleep briefly and lightly—logical for animals that nap out in the open.

Angry Bird Watch

The popularity of the video game Angry Birds, in which feathered friends launch themselves at pigs that have stolen their eggs, may have some people wondering: Do birds get mad in the real world? Indeed they do—especially when their nests are threatened.

Golfers in the Great Plains of the United States regularly risk dive-bombing by Mississippi kites, medium-size hawks that often build their homes in trees near open areas and react aggressively when people approach. Even more common are attacks by mockingbirds. Cats, dogs, and humanswalking near a mockingbird nest, usually in urban and suburban areas, can expect a close encounter with an angry parent and even a sharp peck.

The world champion angry bird, though, may well be the goshawk, a large raptor with needle-sharp talons that breeds in northern regions. The female of this species, when protecting her nest, may be the most dangerous bird on Earth to humans. Biologists working near their nests wear protective clothing to ward off bloody attacks. How nasty are goshawks? Attila the Hun decorated his battle helmet with the figure of one. —Mel White

PHOTOS: PETE MELLA (RIGHT); REBECCA HALE, NGM STAFF

Making Way for Euros

Seventeen European Union countries have adopted the euro since its introduction in 1999, replacing such national currencies as Dutch guilders, French francs, and—as of January 1—Estonian krooni. What happens to all those retired coins? Some are waffled, like this kroon (left), then sold as scrap metal or reminted. But many coins are simply never exchanged, including 41 percent of francs and around 500 million euros’ worth of guilders. Banks call that hoarding behavior, but nostalgia sounds nicer. —Amanda Fiegl

Perceived threats to bird nests can trigger “angry” swoops, like this tern’s on the U.K.’s Farne Islands.

How to Feed a Growing Planet Here’s an uncomfortable math problem: By 2045 Earth’s population will likely have swelled from seven to nine billion people. To fill all those stomachs—while accounting for shifting consumption patterns, climate change, and a finite amount of arable land and potable water—some experts say global food production will have to double. How can we make the numbers add up?

Julian Cribb, author of The Coming Famine, says higher yielding crop varieties and more efficient farming methods will be crucial. So will waste reduction. Cribb and other experts urge cities to reclaim nutrients and water from waste streams and preserve farmland. Poor countries, they say, can improve crop storage and packaging. And rich nations could cut back on resource-intensive foods like meat. In fact, wherever easy access to cheap food means people buy more than they consume, we could all start by shopping smarter—and cleaning our plates.

As Cribb notes, food security is increasingly a collective challenge. It’s also a chance “to pull together on something we can all agree about, share, and enjoy.” —Amanda Fiegl

Food Security

*2008, the latest year data is available. Amounts do not include nonedible food parts such as bones, peels, pits, and cores.

Sea cows are gentle creatures, with few natural predators. Yet the 5,000-plus manatees in Florida waters can’t catch a break. They’ve long been the victims of watercraft, entanglements, and red tide, but now their deadliest foe is low temperatures. Over the past two winters, says the Florida Fish and Wildlife Conservation Commission, hypothermia and stress from cold weather—including the most frigid 12-day stretch in 70 years—have killed at least 400 of the endangered mammals.

Manatees are tubby but lack the insulating blubber of whales. In winter they once relied on warm springs; now they depend largely on the effluent discharged by power plants. Even some off-line plants, like this one in Palm Beach County (right), are required to heat the water to 61°F. But hot tubs can only do so much. More temperate winters would help keep the surrounding waters suitably warm—and manatee populations afloat. —Gretchen Parker

Accidental ArchaeologyA man with a metal detector found Britain’s biggest trove of Anglo-Saxon gold. Here are five cases in which amateur U.K. treasure hunters have turned up key artifacts. —Malcolm Jack

1992Hoxne HoardIn Suffolk, Eric Lawes uncovered a $2.8-million collection of Roman gold and objects, such as this silver tigress.2001Ringlemere CupA plow crushed the gold Bronze Age chalice before Cliff Bradshaw found it in a Kent field.2003Domitianus Coin Discovered in Oxfordshire by Brian Malin, one coin among 5,000 confirmed the existence of a “lost” Roman emperor.2009Stirling Hoard Minutes into his first foray, David Booth found four gold Iron Age neck ornaments in a boggy Stirlingshire meadow.2009Staffordshire Hoard Terry Herbert hit the $5.3-million jackpot: the largest collection of Anglo-Saxon booty ever discovered in the U.K.

The TetherCarbon nanotubes—molecular strands of carbon that are many times stronger than steel—show the greatest promise for a material strong and light enough to serve as a tether. A flat and curved ribbon shape would help minimize damage from space debris.

Photovoltaic Panel

Photovoltaic cells on the underside absorb laser light beamed from a base station; the laser energy is then converted into electricity to propel the climber. Solar cells on top provide additional power.

The DriveLike rollers on a printing press, multiple wheels clamp on to the tether and spin to move the climber along. Maintaining several points of contact on the ribbon helps keep the weight distributed.

Cargo HoldBasic models envision a 14-ton hold about the size of an 18-wheeler’s trailer, but the size could vary, depending on the tether. Aluminum, used in airplanes and spacecraft, is a good candidate for construction.

Space ElevatorIn 2009 NASA’s Andrew Petro watched as a laser-powered robotic device climbed up a cable more than half a mile long above the Mojave Desert. A winner in the agency’s Centennial Challenges program—competitions designed to stimulate innovative research—the setup demonstrated the potential of wireless power transmission. That, along with work on superstrong materials, is creating fresh hope for a vision long the realm of science fiction: an elevator that can carry cargo, and possibly people, thousands of miles into outer space.

First described in 1960, the space elevator was also the subject of Arthur C. Clarke’s The Fountains of Paradise. Construction is still far from viable, but the basic theory is sound, says Petro. Both power beaming and strong tether materials—crucial aspects of the elevator concept—are featured in NASA’s contests and the annual Space Elevator Conference. Another boon was the successful production in 1991 of carbon nanotubes, one of the strongest materials known. But making them suitable for a tether remains a challenge. So why a space elevator at all? Once built, say advocates, it would enable high-volume shipping at a lower cost than rockets. And once that’s possible, the next stop could be colonizing Mars. —Luna Shyr

It’s not every day that a disease disappears, but guinea worm disease may be next, after smallpox. Thanks to international efforts led by the Carter Center, just 1,797 cases were reported worldwide last year, most in what is now South Sudan. In 2012 public health officials aim to push that number down to zero.

The triumph hasn’t been easy; guinea worm isn’t vulnerable to vaccines or medication. The eradication effort’s primary weapon: education. Local volunteers teach African villagers to strain potentially contaminated water through fabric or filter-equipped straws (right). They explain the worm’s life cycle, so that people with emerging worms will avoid entering stagnant water, like ponds, where larvae are deposited. The searing pain caused when the worms exit the body often leaves victims unable to work during key farming periods. But armed with knowledge and tools, communities are close to wiping out this ancient disease. —Nancy Shute

In Ghana, health workers massage a child’s ankle to aid the gradual extraction of a mature guinea worm (above). The worms can grow more than a yard long and emerge slowly, often over several weeks. A preserved specimen (left) is about a foot long.

In Ghana, health workers massage a child’s ankle to aid the gradual extraction of a mature guinea worm (bottom). The worms can grow more than a yard long and emerge slowly, often over several weeks. A preserved specimen (left) is about a foot long.

We like to brag about our gray matter, linking smarts to brain cells. But for neuroscientists, it’s also about white matter, the spaghetti-like tangle of nerve fibers, and the networks that carry information between regions of the brain. Who we are—our memories, thoughts, emotions—derives from these wiring connections. The problem was no devices existed to see and decode the neural maze in live subjects. That’s now changing.

With $40 million in federal support, U.S. research teams are using cutting-edge scanners to create a library of “connectomes”—maps of the brain’s circuitry that promise to reveal how the organ responds to aging, learning, and other events. Data from the Human Connectome Project may provide insights into treating autism and schizophrenia.

In a test image (above), what looks like a clown’s wig is a color-coded depiction of routes created by a brain’s neural pathways. Each strand represents thousands of nerve fibers called axons. The picture’s creator, Harvard professor Van Wedeen, has devised a 3-D imaging process that unveils the connections by tracing the movement of water along fiber tissues. “The brain is so organized,” he marvels. “That’s its true beauty.” —Tom O’Neill

NASA’s Kepler telescope has spied a new planetary system—six bodies orbiting a sunlike star 2,000 light-years from Earth. • Cancer researchers at MIT are developing a tumor-tracking implant the size of a rice grain. • In Brazil tropical fruit fibers have been identified as stronger, lighter, and renewable alternatives to plastics used in building cars. • The Centers for Disease Control and Prevention now puts the average U.S. life expectancy above 78.